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name: simulink-customize-a2l description: > Customize A2L (ASAP2) files generated from Simulink models using coder.asap2 and coder.mapping APIs. Use this skill when adding COMPU_METHODs, creating GROUPs, converting STD_AXIS to COM_AXIS, adding BIT_OPERATIONs, creating VARIANT_CODING, excluding measurements or struct elements, removing DEFAULT_EVENT_LIST, or any A2L customization for calibration tool compatibility (INCA, CANape). Also use when the user mentions ASAP2, ECU calibration data, A2L export. license: https://www.mathworks.com/content/dam/mathworks/license/pmrl/license.md metadata: author: MathWorks version: "1.0.0"

Customize A2L Files

Customize A2L (ASAP2) files generated from Simulink models using the coder.asap2 and coder.mapping APIs, avoiding silent errors and undocumented pitfalls.

When to Use

• Adding or modifying COMPU_METHODs (LINEAR, RAT_FUNC, TAB_VERB, IDENTICAL)
• Creating or modifying GROUPs in the A2L file
• Converting STD_AXIS to COM_AXIS for lookup tables
• Adding BIT_OPERATION (LEFT_SHIFT, RIGHT_SHIFT, SIGN_EXTEND) to measurements
• Creating VARIANT_CODING (VarCriterion, VarCharacteristic)
• Excluding inports, outports, or struct elements from the A2L
• Removing DEFAULT_EVENT_LIST or other IF_DATA blocks
• Any customization passed via CustomEcuDescriptions to coder.asap2.export

When NOT to Use

• Reading or parsing existing A2L files (use Vehicle Network Toolbox a2lfile)
• Configuring XCP/CAN transport layers
• Setting up Simulink model code generation (storage classes, data dictionaries)
• General Embedded Coder build workflows without A2L customization

Core Workflow

Decision: Direct export vs. customization workflow

• No element customization needed (only configuration like excluding struct elements or DEFAULT_EVENT_LIST): call coder.asap2.export directly with name-value options. No getEcuDescriptions needed.
• Element customization needed (adding/modifying/deleting measurements, characteristics, groups, etc.): use the full getEcuDescriptions → customize → export workflow.

% === Path A: Config-only (no element changes) ===
load_system(modelName);
slbuild(modelName);
coder.asap2.export(modelName, SupportStructureElements=false, IncludeDefaultEventList=false);

% === Path B: Element customization ===
load_system(modelName);
slbuild(modelName);

% 1. Create ECU descriptions — pass ALL configuration options here
descObj = coder.asap2.getEcuDescriptions(modelName, ...
    SupportStructureElements=false, ...
    IncludeDefaultEventList=false);

% 2. Customize elements
add(descObj, newElement);
set(descObj, 'ElementType', 'Name', Prop=value);
info = get(descObj, 'ElementType', 'Name');
names = find(descObj, 'ElementType');
delete(descObj, 'ElementType', 'Name');

% 3. Export — MUST pass descObj back or all customizations are silently lost
coder.asap2.export(modelName, CustomEcuDescriptions=descObj);

Critical: When using Path B, omitting CustomEcuDescriptions=descObj in the export call silently discards all customizations with no error.

Critical: When using Path B, construction-time options (SupportStructureElements, etc.) CANNOT be passed to export alongside CustomEcuDescriptions — they must be passed to getEcuDescriptions.

Key Functions

| Function | Purpose | |----------|---------| | coder.asap2.getEcuDescriptions | Create ECU description object (construction-time config) | | coder.asap2.export | Export A2L file with customizations | | coder.asap2.CompuMethod | Create computation method | | coder.asap2.Characteristic | Create characteristic (parameter) | | coder.asap2.Measurement | Create measurement (signal) | | coder.asap2.Group | Create A2L group | | coder.asap2.RecordLayout | Create record layout | | coder.asap2.AxisInfo | Create axis points or axis descriptor | | coder.asap2.VarCriterion | Create variant criterion | | coder.asap2.VarCharacteristic | Create variant characteristic | | coder.asap2.Function | Create FUNCTION object for grouping measurements/characteristics | | coder.mapping.api.get | Get code mapping object (persistent settings) | | setInport / setOutport | Control inport/outport A2L export (persistent) |

See references/object-properties.md for mandatory fields, valid types, and creation order for each coder.asap2.* class.

Pattern Routing

Match the user's task to the correct reference for detailed guidance:

| Task | Key Rule | Reference | |------|----------|-----------| | Add COMPU_METHOD (RAT_FUNC, LINEAR, TAB_VERB) | RAT_FUNC COEFFS direction is PHYS→INT — invert the desired formula | references/compu-method-guidance.md | | Convert STD_AXIS to COM_AXIS (shared breakpoints) | Use ForceShared=true on the Characteristic — do NOT manually create AXIS_PTS | references/customization-patterns.md | | Add BIT_OPERATION to a measurement | Must set BOTH BitMask AND MaskData — either alone produces no output | references/customization-patterns.md | | Exclude inports/outports persistently | Use coder.mapping.api + setInport/setOutport + slbuild | references/customization-patterns.md | | Create VARIANT_CODING | Must create supporting CHARACTERISTIC objects (selection + variant-dependent) with RecordLayouts and CompuMethods BEFORE VarCriterion/VarCharacteristic. All multi-value properties must be string arrays (not char/cell). | references/variant-coding-guidance.md | | Create Characteristic (CURVE, MAP, CUBOID) | RecordLayout struct array must match axis count for STD_AXIS types | references/object-properties.md | | Create Measurement | Set DataType='SWORD', EcuAddress='@ECU_Address@name@', CompuMethodName='NO_COMPU_METHOD' as defaults | references/object-properties.md | | Create Group | See mandatory fields and ROOT constraint | references/object-properties.md | | Create RecordLayout | Struct array required for multi-axis types (MAP, CUBOID); single struct for VALUE/VAL_BLK | references/object-properties.md | | Create AxisInfo / AXIS_PTS | Dual role: add(descObj, axisInfo) creates AXIS_PTS; characteristic.AxisInfo = [...] creates AXIS_DESCR | references/object-properties.md | | Control construction-time options (SupportStructureElements, IncludeDefaultEventList, etc.) | Must pass at getEcuDescriptions() — cannot set after construction or pass to export with CustomEcuDescriptions | references/construction-time-properties.md |

Release Requirements

| Feature | Minimum Release | |---------|----------------| | COMPU_METHOD, Measurement, Characteristic, BIT_OPERATION | R2022b | | RecordLayout, AxisInfo (STD_AXIS, CUBOID) | R2023a | | Group (ROOT groups) | R2023b | | VarCriterion, VarCharacteristic (variant coding) | R2025a |

If the user's release is too old, inform them. Do not attempt workarounds — the APIs do not exist on older releases.

Common Mistakes

These cause silent failures or incorrect calibration data. Always check before generating code:

| Mistake | Why It's Wrong | Correct Approach | |---------|---------------|-----------------| | coder.asap2.export(modelName) without CustomEcuDescriptions=descObj | Silently discards all customizations — no error, exports default A2L | Always pass descObj back when using the customization workflow | | RAT_FUNC Coefficients = [0 0.5 -40 0 0 1] for "PHYS = 0.5×INT - 40" | COEFFS is PHYS→INT, not INT→PHYS — produces the inverse conversion | Invert: INT = 2×PHYS + 80 → [0 2 80 0 0 1]. See references/compu-method-guidance.md | | set(descObj, ..., 'CompuMethodName', name) before adding the CompuMethod | set() auto-creates a placeholder that blocks subsequent add() | delete() the auto-created placeholder, then add() the user's version | | MaskData.Shift without BitMask | BIT_OPERATION block is only emitted when both are set | Always set BitMask (e.g., '0xFF') alongside MaskData | | MaskData.Shift = 3 expecting LEFT_SHIFT | Positive = RIGHT_SHIFT; sign is counterintuitive | Use -3 for LEFT_SHIFT 3 | | Manually creating AXIS_PTS for STD→COM_AXIS | Unnecessary complexity; error-prone struct array handling | Use set(descObj, 'Characteristic', name, 'ForceShared', true) | | descObj.SupportStructureElements = false | Not a settable property after construction | Pass at creation: getEcuDescriptions(mdl, SupportStructureElements=false) | | VarAddress = '0x5000' (char vector) | Char vector silently produces empty output — no addresses, no criterion name | Must be string array: ["0x5000","0x5008"] | | CompuVTabValues.Integers = [0,1,2] | Property does not exist | Use CompuVTabValues.Values = [0, 1, 2] | | CompuVTabValues.Literals = {'A','B'} (cell array) | Accepted without error but exports 0 elements | Must be string array: ["A","B"] | | Skipping slbuild after setInport/setOutport | Export silently produces stale A2L with old settings | Always slbuild after code mapping changes before export | | Hardcoding EcuAddress = '0x0000' | Calibration tools cannot resolve the address at import time | Use '@ECU_Address@<elementName>@' for linker resolution | | Leaving mandatory fields unset on new objects | Blank fields produce invalid A2L — calibration tools reject the file | See references/object-properties.md for required fields per class | | Creating VarCriterion/VarCharacteristic without supporting CHARACTERISTICs | VARIANT_CODING references characteristics that don't exist — calibration tool rejects the file | Create selection CHARACTERISTIC (with TAB_VERB CompuMethod) and variant-dependent CHARACTERISTIC (with RecordLayout) BEFORE VarCriterion/VarCharacteristic. See references/variant-coding-guidance.md |

Conventions

• Verify A2L output with fileread after export — use contains for additions, ~contains for deletions/exclusions
• Use string arrays (not char vectors or cell arrays) for all multi-value properties
• Pass all configuration at getEcuDescriptions() construction time
• Use ForceShared=true for STD→COM_AXIS (never build AXIS_PTS manually for this)
• Use delete(descObj, 'ElementType', 'Name') to remove auto-created placeholders — this is the only recovery from the auto-creation trap caused by set() on a reference name before the referenced object exists
• Prefer coder.mapping.api over coder.asap2 when settings should persist with the model

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Copyright 2026 The MathWorks, Inc.

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